Poly(carbonate-urethane) consisting of alternating carbonate and urethane moieties (poly(HC-MDI)) was prepared by polyaddition of 4,4'-diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3-hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six-membered spiroorthocarbonate 1,5,7,11-tetraoxa-spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate-urethane). The hydrolysis and thermal behaviors of poly(HC-MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND-MDI)) prepared from MDI and 1,9-nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC-MDI) is less crystalline than poly(ND-MDI). Poly(HC-MDI) is more susceptible to hydrolysis than poly(ND-MDI) probably due to the higher polarity and the lower crystallinity. (c) 2006 Wiley Periodicals, Inc.